Field of the Invention
The invention is directed to an image processing technique and more particularly, to an image processing apparatus and an image processing method.
Description of Related Art
Banding artifacts (or false contours) often occurs in an image after quantization of the intensity (e.g., chroma or luminance). With the increase of display sizes, the false contours become more obvious. Before a false contour is removed, a system has to perform false contour detection on the image in advance. False contour are low-frequency components in an image while edges and textures are high-frequency components therein. Therefore, in a conventional method of detecting the false contours, only gradient-based method is commonly adopted to separate the false contours from the edges and textures.
However, a change of small details (e.g., weak edges and fine textures) in the image is approximate to a change of the false contours. The conventional method cannot distinguish the small details from the false contours. When a weak edge (for example, a cloud in the sky) or a fine texture (e.g., fur of animals or a grassland) is mistakenly detected as a false contour, the weak edge or fine texture will be smoothed. As a result, the conventional method of detecting the false contours would lead to loss of part of the image details.